Grudge Effect on Paint

Start out by selecting the airbrush tool (). Select the largest possible size and your color to black. Now, begin randomly smearing around your canvas -- just make sure you don't hit the borders. Your image should look sometime like this:

Next up, use the paintbucket to make your background color black. Then, use it again to make your background color back to white. Your resulting grudge will look something like this:

Thats it -- your done. You can use this grudge as a bursh, on paint as a texture or on a different program. The choices are endless. Use your creativity and you'll think up something great :).